Pain in the thumb. Equations and notes.

I have this pain in the thumb since ten months. I consulted my thumb to the orthopedic and he suggested me to wear a thumb splint as nothing showed up in MRI and x-ray. Wearing the thumb splint did help the pain reduce momentarily but the pain wud haunt me if I ever tried to bend my thumb. I then consulted with a hand surgeon and he too couldn't help. I then decided to give my thumb a complete rest. After 8 months of rest I could feel less pain. I can bend the thumb without much pain now, but accidental folding of my thumb would pain again. I feel an excruciating pain while/after writing. Please suggest me the right treatment/remedy to fix this. I am a PhD student and I can't help but to use my right thumb in writing a lot of mathematical equations and notes. Thanks in advance