3 yr old with staph infection and now complaining of legs and bottom hurting?

[Sa Hm]

About 6 days ago I noticed a bump on my sons finger which I thought was just a hang nail. I took him to the dr about 2 days ago and found out he has staph which he has had twice before. They put him on antibiotics for it and drained it, when they drained it, it was still blood so they said that was a good sign because there wasnt anything else in it. Anyways, tonight he came up to me and told me that his legs and bottom hurt. (like the front of his thighs) so i called a bigger hospital and they had me call a call center, which the lady told me that its not normal for a 3 year old to have leg pains and she would take him to the dr tonight because the staph may be spreading. So I called out to my local ER and they told me to give him tylenol and to see how he is in the am and take him to the dr if i want to. (which the lady thought for the first half of our convo i said he had strep.) but said since he is on antibiotics and no fever she wouldnt be worried but I could still bring him out. Is there something I should be worried about?? I worry about everything so sometimes I over exaggerate.. Does it seem like it is getting worse? He can still walk and everything fine and is in a great mood... but just says every now and hten that they hurt.