Water pressure acting weird

Hello fellow homeowners. So, I have well water at my home (living in midwest USA) and in the last week, the pressure has been pretty consistently 10psi below normal running pressure. Awhile back, I was having issuss with it dropping as low as 20 and not climbing unless I smacked the pressure switch. I finally got around to replacing the switch and since then, it's been working how it should, 30psi on the low end and 50 when we're running it. What could be holding that last 10psi out? TIA