Sounds like scale, they're a sap sucking insect with a bit of a hard shell over their back. There are insecticides for them and you can also rub them off with cotton buds dipped in alcohol. But you have to check thoroughly all over the plant and in all the nooks and crannies for any hiding that might later breed up again.

it's too late to be adding organic nitrogen if you live in zone 7a it will push too much new growth before the wood can harden off for winter. get through this season and fertilize in spring. it's perfectly fine to be a little depleted on N if growing figs outside of zone 8. in ground. organic fertilizer takes weeks to be taken up by the plant and thus feeding the plant over a longer period ie 3--6 months so use manures and meals about 2 weeks before the first leaf pushes out and use compost tea for a boost throughout the season if you feel the need. but again give your tree time to stop growing before the first frost. the dark color wood is what you want to see on over 90%of the tree by te 1st of october. or it could die to the ground or die all the way. mulch around your tree and only water once a week. next year if you keep it mulched you may not need to water it at all. inground figs trees take neglect well and clay holds tons of water so the trees will be fine going 5-7 days between watering just be sure to use at least 4 inches of mulch or better and keep the mulch off trunk of the tree. also only water the soil not the leaves or you'll get rust or other fungal diseases on the foliage. good luck, and don't go broke buying all that expensive crap at organic stores a little lime and compost go a long way my friend. growing organic is supposed to be cheep but big business has stuck there greedy hands in the mix and now it's just stupid at what they try to tell you need to grow things properly. I'd never use fish emulsion because raccoons are attracted to i fish and they will eat your ripe figs if there happen to be any at the time of his visit. I'd never buy rock dust, seaweed powder and all that other crap. people have been growing things for thousands of years without the need for such things. I'm all for feeding the soil but again compost goes a long way and the more diverse the compost the better. if you don't have a compost pile , bin or tumbler start or invest in one instead of wasting your money on nutes at the garden center.

Hopefully I can get some pictures tommorrow . It doesn't look like raspberry mosaic from searches I have done. Looks more like tomato blight

Update: Mystery solved! I came back home from a trip a week ago, and found the tree had dropped a third of its leaves. On closer inspection I noticed spider mites on the top of many of the remaining leaves. I’ve had spider mites on multiple plants before and usually catch them early as I see the tiny red dots and clean them off. Weeks ago when the yellow spots first appeared, I had looked very carefully on the whole tree and didn’t see any mites. Even zooming in on the photos above, I can’t see mites, although I can see a little bit of stippling. My guess is that they were at a stage I couldn’t see, or were a different type of spider mite than those I’ve seen before. I took the tree outside and treated it with insecticidal soap. This time when it was wet, many tiny webs became visible in the branches - it was heavily infested. I wasn’t sure if the spider mites had infested the tree after it became sick with the mystery yellow spot disease, but on Wednesday I got an email from the agent at the Florida agricultural extension that had responded before, saying she thinks the issue is spider mites! - She had just seen a presentation where the yellow spots were shown as a spider mite symptom, although an unusual one. I really appreciated her following up. It has been a learning experience - I now know that I can’t rely on visual inspection for spider mites, and that if yellow spots appear on a plant, it is a good idea to treat it with neem or insecticidal soap to be safe. I’ve treated my other trees and will repeat treatments on this key lime every few weeks until I’m sure they are eradicated. Hopefully it will survive - it produced a great crop this year. Thanks everyone for your help - and John, thank you for your suggestion of checking for spider mites - I should not have assumed that if I can’t see them, they are not there! Happy holidays!