Suggest Treatment For Severe Lower Back Pain Experienced After Periods

Hi I've just had a failed ivf cycle.
Also just finished my period from the failed cycle.
I've got really sharp pains in my lower about and severe lower back ache... I also suffer from endometriosis but this pain came. On all of sudden.. Slightly different than my endometriosis pain which I can feel coming. On slowly and then gradually gets worse.
I've had strong medicines it hasn't even taken the edge off at all
Don't know what to do now.