How can i test for a rcl sprain in my thumb? like a laxity test or stress test or whatever i think it's a grade two but don't want to go to the dr.

Thumb sprain: Best to get it checked, but try 45 degree flexion stress.

See below: Miranda, to test for an RCL sprain, hold your hand with the fingers extended, palm down. With your other hand, gently push the thumb toward your index finger while resisting slightly. If you feel pain, the RCL is probably sprained. It is still a good idea to see a doctor in order to get an Xray, to be sure you don't have an avulsion fracture (where the ligament pulls off a chunk of bone).