I'm scared --is this angina?

Hi-Im 46 yrs old female and a little scared...About 4 months ago I found I was having difficulty breathing while laying flat. I added a pillow (to my normal 2)so I could sleep on an incline--that lasted about a week before I added another pillow. THAT incline lasted about a week before I added a 3rd pillow. I'm currently holding at 5-I'm basically sleeping sitting up on the bed. (to be fair-2 of these pillows are on the flatter side)

About 2 months ago I ran down the stairs and out the back door...I experienced a feeling I had never had before: I had to stop-literally stop in my tracks...I was breathing heavy-trying to catch my breath-- and felt a squeezing in my chest. It then went into pain--a pain that went thru my back. That ws horrible pain from my chest to my back. (back pain was between the scapulas.) Clutching the chest and try to breathe sounds so cliche-but its really all I could do til this passed. And it did pass--the feeling does finally go away if I sit down or take a few mins to breathe on my own. It started out that I only had this when I was going up or down stairs--but now over the past month I have felt some tightness out of the blue, at rest, along with weird palpitations that have increased in frequency and intensity over the past month. (I've had palpitations for years-but was told years ago that palpitations are nothing to worry about so I never saw a doctor for them.) When I was a child I was told I had a heart murmur that could be heard only when I was laying down. 4 yrs ago while having a pre-op for minor surgery, the hospitalist had me laying down, sitting up and standing (a few times each)while listening to my heart--he asked me I had a heart murmur --and I said yes, only when laying down. He said that's when he heard it too and it was nothing to worry about. I might add that, I am average height / weight (5'4"--135 lbs) and smoked abt a 1/2 pk of cigarettes a week (socially when I had a beer or two) until 22 years ago when quit. I drink so infrequently I cant remember when I last had a half glass of wine. For about 6months, ending in February this year, I ran 3-5 miles 4-5 days a week--with no problem-no chest pain -nothing.

SO-what the heck is going on? Does this warrant a trip to my doctor? And if so, why and what can I expect? I don't want to go--altho I do like my doc. Just not when he's seeing me! I really am nervous but don't want to be thought a hypochondriac or a fool for coming in with no 'real' problems. miles 5 x a week. I have never felt this before--and just plain scared.

Thanks so much for your help!