Is this anxiety or am I just stressed?

Growing up I never had panic attacks or anxiety but 2 years ago I went through something pretty traumatic while I was over seas and when I got home I started experiencing panic attacks. Recently I've started to get this really heavy feeling, I don't really know how to explain it but my head starts to hurt and I find it kind of hard to breath but it's different to the panic attacks and it will just happen randomly not when I'm in certain situations. I will just be laying in bed and I can't shake this heavy thigh feeling in my chest and I don't know what to do. I just want to cry but I'm not really sad about anything. I'm so confused