Pregnancy Symptoms.

I'm just wondering if its possible to experience symptoms a few days after (possibly) conceiving? Me and my S/O had unprotected sex during ovulation and i've been having serious cramps/backache, even though I'm weeks away from my next period. I've also had bad constipation, too. I know, TMI, but it's unusual for me. 😣 Just wondering what opinions you ladies had. 💙