Thanks for the query.
During perimenopausal period some amount of irregularity is common in menstrual cycles due to fluctuation in the hormonal
The other symptoms you mentioned like abdominal cramps, diarrhea
etc. could also be due to some gastro-intestinal cause.
So you once consult gynecologist, get examined and go for one ultrasound
. With this workup the possible cause for your problem can be identified and treatment can be given accordingly.
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429