There are several possibilities. One possibility is Exobasidium Leaf and Flower Gall, Exobasidium vaccinii which is a very common fungal disease in the spring during wet, humid, cooler weather on azaleas and occasionally on rhododendrons. In April and May leaves and buds of infected plants develop distorted growth. Another is Long-tailed Mealybug, Pseudococcus longispinus which creates small cottony masses with long, waxy filaments extending from one end is a symptom of the long-tailed mealybug, Pseudococcus longispinus, which is a sucking insect that colonizes on the least accessible parts of plants. Since it is hard to see, systemic insecticides are preferred, but thorough treatment with a contact insecticide may provide control. Infested plants will have honeydew and sooty mold (black coating) on the leaves. Terminal leaves may become yellow and distorted, and dieback may occur. Infested plants are usually growing in sheltered locations, such as against south facing walls. The mealybugs may be found on lower leaf surfaces and stems. Adult mealybugs are about 1/8 inch long, and covered with white wax. The body margin is ringed with white wax filaments, with the last pair over 1/2 the length of the body. Immature mealybugs have short wax filaments. This mealybug feeds on pyracantha, holly, yew, and rhododendron. There are two to three generations a year, and the immatures over-winter on the bark. Inspect plants for beneficial predators such as ladybird beetles. Some immature ladybird beetles may resemble the mealybugs, but move faster. If the mealybug problem persists, ant control may be necessary. Ants feed on the honeydew secreted by the mealybugs and protect them from parasites and predators. A third possibility is Thrips, Thrips imaginis. This insect is a seasonal pest, causing most damage in mid to late summer. Signs of damage include silvering of the foliage and distortion of growing points and flower buds. The underside of leaves may be covered with excreta of the insect, which are like brown tar droplets. There are no effective specific biological controls and thus control can be difficult to achieve. Thrips are preyed upon by ladybirds and lacewings but these predators cannot control thrips in plague situations. A fourth possibility is Rhododendron Gall Midge, Clinodiplosis rhododendri. Clinodiplosis rhododendri usually over-winters in the soil as a prepupa. Pupation occurs in spring, with the adult midge emerging just as the hosts begin vegetative growth. There may be two additional generations yearly corresponding with flushes of rhododendron growth. Eggs are laid in clusters on the undersurfaces of leaves that are emerging from buds. Larval feeding causes a downward and inward rolling of leaf margins. Larvae mature in about seven days, drop to the ground, burrow in and make a cocoon.

In my region, we have a relatively new pest, the azalea lace bug. This very small, nearly invisible because of its translucence, true bug has piercing sucking mouth parts, works from the undersides of the leaves and can "bleach" a rhodie or azalea in less that a season. Stressed plants seem more vulnerable that others. Here's info from Univ of CA http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7428.html Here is a link that might be useful: azalea lace bug

It is relatively minor. However, new damage appears because I watch my plants. The plants were small when I bought them from retail store. I bought them in 1/4 container. There were NO mechanical damage during transportation. I did research, and I know that leaves can be deformed if roots were eaten by larvae or grubs. Brown discoloration is caused by sap sucking insect because I used insecticide on leaves and it helped a little bit (less damaged leaves on two shrubs). Probably, "eggs" is slow release fertilizer because these eggs are scattered around the pot and in a bag of Miracle Grow Garden soil. Anyway, I will solve problem by contacting entomologist or plant pathologist.

Two recommendations: Move and Raised Beds. Neutral soil can be amended, but alkaline soil is best to avoid with a raised bed. The good new is that azaleas have shallow roots so the raised bed need not be too high. I am going to send you the link to my website which has sections on moving, raised beds, lace bug, etc. It has an index to these topics. Here is a link that might be useful: How to grow rhododendrons and azaleas