I'm Overall Pretty Healthy, For The Past Two Years Since

I'm overall pretty healthy, for the past two years since I was about 11 or 12 I've had bad chest pains in the left side of my chest at random times and lately in the last 6 months it's become a lot more frequent. I would be sat watching TV or in a lesson in school and my heart would feel like it's beating hard (not fast, but almost like a soft punch against my chest type of feeling) and then the left side of my chest would start to ache. Another thing I've noticed is that when this occurs I start to feel sick and dizzy/light headed and it feels as though I'm struggling to breathe. Both shoulders would feel heavy and I'd start to get a headache. Usually this "episode" would last about 30 minutes to an hour, but on rare occasions could last up to 4-5 hours. No painkillers or heart-burn relief helps the pain either.