Tendinitis takes a long time to really resolve - that's the experience i'm having right now.

And if your tendons are tight AND you've been off the bike for a long time...it's going to hurt. Changing your cadence/etc won't help - you need to loosen the tendons and strengthen the muscles.

After a lot of physical therapy, i'm doing a series of regular stretches for hamstrings, quads, and IT bands. that might help you.