Constipated! what should i do?

i haven't had a decent bowel movement in like a week. i've had chronic constipation pretty much all my life but i haven't been this backed up i a while. for the past week i've been drinking between 2-3 liters of water a day and eating fiber plus bars, raisin bran cereal, whole wheat/whole grain bread, apples and some cherries but nothing is working. i took 2 colaces yesterday & 2 today, as well as a mild laxative last night, and all i got this morning was thin pencil stools. idk what else to do and im getting worried & im very uncomfortable. i went to my doctor today for a check up and she told me to just up the dosage of the miralax. is there anything else i can try?