A tendon strain is one of those things that can really only be healed up by letting it rest.
Any kind of exercise will likely prolong the recovery time.
I've had to deal with them & it sucks.
Aleve, some light stretching, & lots of down time are about the only things that consistently help.
@Snarky_succubus and I go to a chiropractor that works on very high level athletes. He has had success in working the whole area, from neck/trap all the way to my thumb. But, again, it takes time.
Massage and pressure point work had about zero percent effectiveness on me... But, everybody's different.
Good luck to you.