Hi there, I have a painful area under my foot when I apply pressure on it. When I looked yesterday I also saw a black spot on the same foot next to where the pain is but it’s not painful and it looks to be under the skin. Should I be worried?

No. No, I would not worry about it, but I would definitely be seen and thoroughly evaluated for it. Multiple potential causes.
Probably not. Depends on where the pain is. Under the heel it could be plantar fasciitis which can be very challenging to treat. The black spot could be something like a naevus which must be evaluated in terms of malignancy risk. So better to consult your gp.