Sudden period pains

[akmum18]

I don’t have periods often usually every 2-3 months then a 6 month or longer gap etc due to pcos, but when I do they are light flow and over in a few days, no cramps or other problems.

I have just come on and having the worst pains, I feel nauseous with it and look 6 months pregnant. (Definitely not pregnant - single mum and not sexually active or on contraceptives) this has never happened to me before so I don’t know if it’s what women typically experience. Should I be concerned?