Hello @cupcaker, Welcome to Mayo Clinic Connect. I have not had a hip replacement but I had a knee replacement last year and it feels like I'm close to needing a hip replacement on the same side. The pictures certainly look like it could be an infection but then I don't have any medical background or training. I did find some information that you may find helpful.

Joint Replacement Infection: https://orthoinfo.aaos.org/en/diseases--conditions/joint-replacement-infection/

@marysapp, @mrcapri, @melar1, @lynnd1961, and @scottjeffe have discussed hip replacements and may have some experience to share with you.

Have you mentioned to the doctor or surgeon that the area you painted in has grown as you might suspect if it's an infection?