31, female, smoker, have been a substance misuser of cannabis for 10 years, although gave up 14 months ago. 5'2 , 11 stones, recently (2 weeks) started traing/ swiming going to the gym, last 2 days i have had what feels like pulpitations in my arse, feels likes its right up my rectum, not painful but like heart pulpitations (which i have had on and off since coming off drugs) really irratating.. im just not sure if this is a problem? Hope you can help.