I got a dental implant a week ago. I see/feel a hard white spot. I've taken amoxicillin since. Can it be an infection? (Photo)

If it is hard it is possibly bone.  It has only been one week so I would not panic, but I would definitely call the dentist who did it and get in to see him/her to evaluate as soon as possible

That appears to be bone sticking through the gums. This can happen for many reasons and it's important you go see an oral surgeon to assess the situation before you lose more bone and possibly the implant.