So far, I've went through three "possible" diagnosis........first of all, I was told I had pomphlyx on my hands and feet, then the Dermo decided that it was PPP (palmo plantar psoriasis) and now she's querying tinea. I think her indecision is because none of her treatments work!! I've tried every lotion, potion, cream and ointment that the doc can think of and none of it has helped. She is now treating me for tinea, and believe it or not.........that's not working either!!! I can't understand why she thinks it's tinea because she took some skin sample (ouch, ouch) and said that absolutely nothing grew (which means there's no fungal infection there). It might be worth asking your doc to do this too - to see if anything grows. If it doesn't, then it rules out tinea.
PUVA treatment has been mentioned for me, but as yet, nothing has been done about it. With a bit of logical thinking, I spent time either with my feet in the sun during the summer and I tried a couple of sunbed sessions too. Like you, it dried up the existing blisters but new ones just formed elsewhere.
I'm sure I read somewhere that if your nails have little pitted marks on them, then it's a sign of psoriasis and I'm very much thinking that that's what I have - having compared it to others and the fact that my nails are now growing in pitted.