Listen to Xenorikki! It has happened to me a few times. Ice the area to get the swelling down. Then wrap your shoulder w a heating pad. Do it every night and don't work upper body for a week. ( until it is healed) Every time it happens to me over the yrs., it took about a week or so. The ba irritated the muscle and caused it to swell up and sometimes become stiff. You'll be fine bro!
Ice is an option for sure, but if the infection is caused by the product itself, seeing a doc is the best option. So many complications can arise in case an infection is not treated the right way. It is crucial to do things in time.
At the same time, preventing is way easier than treating. Just do your homework and check your source before shopping.