For about 11 years i have gotten painful blister like bumps on my inner thighs and armpits. multiple drs don't know what the cause is. any ideas?

See your doctor: Painful blisters needs to be seen by your doctor to document location, size, and type of bumps/blisters. If needed, they can do a scrape biopsy to find out what it is. By itself, it's hard to determine, and you may be referred to a dermatologist who can pinpoint it right away and take care it. It's impossible to determine without seeing it in person, by your doctor first.