Alejandro,

I believe that I can give you some alignment suggestions that might improve the situation.

In parsvottanasana, a common tendency is for the head of the humerus (arm bone) to move with force in the anterior direction (toward the front chest). This is taking the arm bone out of the shoulder socket. This can put a strain on the rotator cuff muscles that are meant to keep the arm bone in place. (It is most likely that you did not injure a deltoid, but actually a rotator cuff muscle under the posterior deltoid.)

The best way to come into the pose is to try to always keep the head of the humerus up (side body long) and back (toward the back plane of the body). This is best done by resisting the elbows forward (toward the front of the body), and once the hands come to the back, press the little finger side the hand strong forward into the back to help leverage the head of the arm bones back.

If you have inflammation remaining in the shoulder, it is not surprising that you get pain in chaturanga and urdhva mukha svanasana. I would suggest icing it, etc.

You can also make chaturanga dandasana and urdhva mukha svanasana less weight bearing by coming to your knees first in chaturanga and substituting bhujangasana (cobra) for upward facing dog.

For both chaturanga dandasana and urdhva mukha svanasana also keep the head the humerus to the back plane of the body. For example, do not let the shoulders dip lower than the elbows when coming into chaturanga.

I hope that helps.
Scott