Thanks for the query to H.C.M. Forum.
We in general terms call it as false labor pain
Due to contraction of uterus
there develops irritation of diaphragm .Diaphragm irritation causes pain in shoulder joint because of phrenic nerve
( same nerve supply of shoulder and diaphragm).
Contraction of uterus also causes pain in vagina .
Once uterus came in its original position , you felt better.
In my opinion need not to worry as these symptoms are common in pregnant females.
If pain recurs then consult a gynecologist and get his opinion.
Good luck. Dr. HET