Constipation in toddler

I was wondering if anyone has any suggestions on what to do with my child? My name is Joselyn and I have a 20 month old son, Freddy, for the past 2 weeks has had trouble having bowel movements. A little over 2 weeks ago he started getting fevers so I took him to his pediatrician and they tested him for strep and flu and he tested positive for strep. He was perscribed amoxicillan for 10 days, which we only did for 7 because of the constipation. He stopped eating alot of his regular foods, which I thought was due to strep throat and he also stopped having bowel movements (this was actually a problem about 3 days before the antibiotics). I thought since he wasn't eating well then maybe that had something to do with not having a bowel movement. He went without having a bowel movement for 4 days and then I gave him a tummy massage that I had learned in baby massage class to relieve constipation. The following morning he had a bowel movement. However, after that he didn't have a bowel movement again so on Monday (it had been about 5 - 6 days since his bowel movement) I took him to his doctor again. She told me to administer a glycerin suppository and feed him raisins. I gave him the treatment and he had a small bowel movement 1 hour later. By wednesday he still hadn't gone on his own so I called the doctor and she told me to administer a childrens Fleet enema. I went ahead and did this and he then had a large bowel movement 1/2 hour after the enema. He also ate well that night, he