BWT,
Sorry to hear you are having trouble.
I hurt my hand years ago on the Captains of Crush #1.5. I ceased using them and my hand recovered in a week or so, but I was scared enough of the Captains that I didn't use them again for years. I already had tendinitis when that happened.
Getting over the tendinitis (I feel like I am almost completely over it) seemed like a matter of time, continuing to do dry and live fire as much as I could, massage, and stretching. Also, getting the Thera Band Flex Bar over a year ago also felt like it made a huge difference. Since December 2014 I have been doing the exercises recommended for both medial and lateral epicondylitis, to both arms. Three sets of fifteen, both arms, both sides of elbow on each arm, about five days a week. My subjective sense is that this single thing is the biggest factor in reducing my tendinitis and keeping it at bay. And not doing draw practice for literally hours at a time. That feels helpful too.
I am not a doctor, nor have I ever consulted a doctor about tendinitis. I learned the exercises I am doing from this video:
I've resumed using the Captains of Crush (allure of moar grip strength...) but am trying to be very very careful. Been doing one or two sessions per week with the T and #1, with both hands. I stretch hands and arms before and after. About 5 repetitions each hand with the T, which feels very easy. And then up to 5 repetitions with the #1 (so far have been mostly cutting these short by a rep or two, and accepting reps where I don't get it fully closed.) Plus the green Thera Band Flex Bar about five days a week as discussed. Stretching and massage to hands and forearms almost daily. And once or twice a week, I put a plain old rubber band around my fingers and hold them open.
Since it sounds like you have an actual problem, I think you should do better than I did and probably go consult an actual doctor.
Good luck!