2 yr old intense fear of doctor/clinics

Hi, I am hoping for some advice.  My 2 yr old son has never been fond of the doctor's appts, but got through them with some fussing.  About a month and a half ago, he had a constipation (though bowel movements most everyday) issue.  Our family physician, who I do trust, ordered an enema and when we left the hospital had us watch him closely for a fever or bloody stools.  Neither of those developed and his bowel movements have been good.  Anyhow, he threw up the other night several times, then woke up feeling fine went 2 days with no problems (some diarrhea but expected that from being sick, we both had it) and last night he woke up with vomiting again.  He seems great now, holding everything in, playing, plenty poo in his poo, BUT I would like to have him see the doctor in case there is a bigger issue.  The problem is when we even enter the town the medical center is in, he cries and shakes so bad he burst little blood vessels all over his face and throws up he gets so terrified now.  We tried meeting at a rural clinic, but as soon as we walked in he  recognized it was a clinic.  He does the same thing with churches as well.  Is there anything that you can suggest? And maybe whether or not this occurs with others?