Is my prop not sterile

I got two bottles of the Mexivet Testopro which is 50ml of 75mg/ml. I finished the first bottle and was getting real good gains. I was not getting and injection pain and no sourness at the site the next day.

I have now using the second bottle for the past two weeks . So far, every injection has been uncomfortable and I get an uncomfortable sourness at the site the next day or two. Then the pain goes away. Why is this happening now? Is it because the second bottle is not perfectly sterile as the first?

oh shit, that scared me reading that presser. I don't want to go to the hospital. But, yeah the pain does go away in a day or two. That would be actually cool if indeed it is stronger in content. I'm already happy with the gains, maybe I'll get even more now.

It could be the BA content is a higher ratio than the first?
were they from the same lot #'s

damn I don't know if they were the same lot #. I threw the first bottle away when I finished it. I don't like keeping anything around.