My son has suddenly stopped self-soothing himself to sleep

My 7 month son was really great at putting himself to sleep. We would put him in the crib awake and he would fall asleep. This last week he will no longer self-sooth. He scream when we lay him down in his crib and will continue to cry until we pick him up. I tried to let him cry it out but after a while It just broke my heart. I rub his back and try everything to smooth him without picking him up. Is it just a phase or have I lost my good sleeper. I guess mostly just venting but if anyone has positive advise I would like the help.