I don't feel well

So I have this feeling in my stomach and it won't go away. It's not like a stomach ache, but it's more naggy feeling? I've had it for a while now 9-10 weeks My period has been a week to four days late in the two months of having this. by any chance I'm just causing problems in my head? I realise how silly this may sound but I was wondering if anyone has experienced this before?