What Causes Continued Flushing Of Chest, Legs And Cheeks?

I have been having some flushing of my chest, tops of legs and cheeks dor about 5/6 years. I have noticed it but never was a concern to me cuz it didn't happen often. Within the past 8months for about 3 weeks back in Sept I was having to go to the restroom 5/6times a day. Then it went away. And have not really had to big of a problem with it since. I noticed about a year ago really bad stomach pain that lasted 24hrs. But then went away the past week I just had it happen to me again. My flushing on my chest and cheeks seem to be the worst when I am stressed or upset. But sometimes just at random too. I also within the past 3 months started having my heart race all the time like 90-140 sometimes when I am doing nothing and makes it feel like I just can't breath to well. I am in my 20's and have a clean bill of health. I have seen to internal medicine docs. And one tested me for carcinoid syndrome. They did the urine test, blood and a ct scan on my abdomen and all came back normal.I am still having the flushing skin and raising heart I am recently going to a new doc. Who thinks I have the same thing and is doing all the same steps again...is this a very deadly cancer? Does everyone have to do chemotherapy? Or do they just remove the tumors if any are found? They say its a rare cancer I just need some more advice on thinking is this the only thing it can be. I