1 antibiotic pill isn't going to do shit for the swelling IMO; I wouldn't bother. If there is no infection, antibiotics are doing nothing good for you.
Just take naproxen or ibuprofen OTC at the RX dose for a few days up to a week or two (if even needed that long). A topical corticosteroid can help too, esp. if you can get your hands on an RX grade one. One of my friends had a bad RXN to an oxandrolone/stanozolol suspension shot and said that topical clobetasol (strongest topical corticosteroid) helped a lot. If not, the weaker OTC shit like hydrocortisone 1% -might- help; I don't know. The NSAIDs will definitely help with inflammation and pain and swelling, given time to work. As long as you are getting better (even if slowly), then you probably don't have anything to worry about other than getting the RXN to subside, and for that just take an NSAID until it improves (basically what my doctor told me).
I have a high pain threshold too, but I got fucked by a certain brand of tren e and had a bad reaction and was in agonizing pain for a few days and swelling and redness and inflammation for about 10 days. I tried shooting the same brand again a week later into my glutes and the exact same shit happened, so I got rid of that tren e and moved on. If you keep getting severe reactions, to the point you can't even workout (etc), then it might be prudent to get some new/different test.
Just my $0.02.