Sounds like ligument damage to me
I know you hate it but very careful cross-taping w/ thin strips should help and at least keep you moving.(Take 15 minutes to get it 100% perfect, practice better cross-taping: it's difficult to get it just right, and don't use cheap thin tape - use expensive real hospital strappal)
My most recent copy of Climbing magazine (US) mentions "H taping" as bossest bandaging method around - supposedly there's even some science to back it up. I vaguelly recall that it involved taking a 10 cm long double-width piece of tape and slitting it longitudinally from either end - leaving a short bridge (~1cm) in the middle. The bridge is put against the underside of the knuckle and the joint wrapped either side using the "arms" of the H. I'll try to did up an electronic version.