Frustrated!

So, somehow I pulled an oblique muscle. I did not feel any discomfort until about 12 hours later.. which is weird. I did some yoga the next day to see if stretching would help. Woke up this morning, still painful, worked out anyways (trying to avoid the core.. HARD TO DO). I also did some upper body work and immediately noticed the joint at the front of my shoulders was hurting…it eased up but still felt very tight and sore. I don’t see why I am having so much trouble! I am in good shape, but seem to be injury prone. I am sure my body is telling my something, but I hate not being able to move my body like I want! Anyone else have similar experiences?