I Have A Known Irregular Heart Beat. Drops To 35

I have a known irregular heart beat. drops to 35 then back up. Lately I have felt weight or pressure on my chest area and yesterday I began to have severe pain in upper back or shoulder blades so I am thinking I pulled a muscle but aleve and ibuprofen do nothing. I have an apt with a cardiologist middle of May and I called and they can not get me in sooner. Wondering if I should have it checked out at urgent care