Pimples are always a tricky subject, as you say, finding out the cause of the problem is really important. The other thing that is really important, is to establish whether or not the problem (ie the pimples) is there all the time? Or does it come and go? There have been some amazing developments in the treatment of acne and breakouts, such as the Clarity Range from Lamelle. This range has products which are great as spot treatments, as well as products which can be used daily if you have constant breakouts.
Whether or not the problem could be acid related? Again, I would say some more analysis is necessary… You very best bet, would be to go and see an aesthetic doctor who deals with problem skin and have a proper consult so as to ascertain the cause. This will obviously allow you to have the very best treatment possible.