So I have anxiety disorder and am on celexa 40mg. My anxiety stems from my heart rate and fearing I'm going to just keel over and die. A few weeks ago I had a series of bad attacks that lead to my mental health deteriorating completely. I've had multiple EKG's in the past few weeks for fear of heart palpitations. Ocassionally when I check my pulse in my neck it'll feel like it beats rapidly a few times and then goes back to normal. I never feel any chest pain or other symptoms that could indicate an actual health issue leading me to believe it's just muscle spasms. But, over the last few days ocassionaly when I check my pulse, for a few seconds the muscles around where I check my pulse seem to lose control and almost feel like twitching jelly. I've taken this as my possible heart palpitations may be getting worse although my pulse feels normal and steady throughout this spasm. 

Has anyone had anything similar or any knowledge on what this could be? I want to get a holter monitor in a few weeks but I'm terrified that if this is something serious I could be too late.