Chest pain and heaviness in both arms?

Obviously I thought I was having a heart attack to start with but now i'm not sure. I had slightly weak arms yesterday as if i'd been holding them up for too long. Today I woke up and felt a bit dizzy and my arms felt heavy (kind of like I'm getting a cold or the flu). I've been sat in bed all day doing work on my laptop so I don't know if that's made my arms feel worse because I often get a sore neck or headaches from my sleeping and sitting positions. They've started feeling more heavier this evening and weirdly feel worse when I lie down. But later today I start getting a weird tightness/pressure in my chest. It's not really a pain but it's obvious enough for me to be a bit worried. It feels worse when I take a deep breath or laugh. I'm a 19 year old girl, average weight and a non-smoker or drinker.

Don't know if it's related but I am due on my period and sometimes feel a bit dizzy beforehand.