Newbie with Pain!

I'd hate this to be my first post! Moreover, i knew this has been discussed many times before.. but the threads are so many it's hard to find what I want! I am an amateur 34yr old swimmer doing 3 times a week training program for the last three months.. Eventually as i increased pace and program, i started having swimmer's shoulder pain.. I do more freestyle swimming and try to variate pace/prgram every while.. I do about one hour and some 2.5km per session with many combinations.. (hope my calculations are right!) My question is: 1) should i quit for a while till the shoulder pain goes away 2) should i continue lightly and do shoulder exercises 3) is it necessary to see a doctor/.. Other comments really appreciated! Thanks, wael