TTC #3 af problems. Help or advice needed pls

[2011Maybebaby]

Hi there. Just wondering if anyone can shed some light on my af. I am 42 and have decided to try for no 3. That was in Feb. I already have two boys, aged 4 and almost 3. Got pregnant on them in month 3 and month 1. Two emergency c sections. After having my second little boy, my af has been longer and more painful and my cycle has become a few days shorter (now 26-27 days) I'm also getting cramps on and off throughout the month. Anyway, on to this month. I was due af on thurs, no sign. Bfn on tests. Last night I could feel af coming but I started getting 'contraction' pains where I couldn't walk and felt nauseaus. The pain was constant and is still 50% there today nearly 24hrs later. Has anyone ever felt this or have any ideas what it might be??