1. going through your history, it seems that you are suffering from tight foreskin of penis.
2. due to non retractable foreskin, a white substance called smegma
collects under the foreskin and is susceptible to infection [thrush], which may cause pain/bad odour.
3. cream which he might have told/prescribed would be Betamethasone
1% ointment, which can be applied to the tight part of the foreskin and will speed up the stretching process.
4. stretching instructions depend upon the type of tight foreskin [either phimosis
or paraphimosis], since not given in the history, so you have to make an appointment with the doctor who will evaluate your condition and type of tightness and then will recommend the type of stretching you have to perform.
In the mean time, one thing common in both the techniques [for phimosis, paraphimosis] is soaking in warm water before performing the stretching, so one thing can be safely advised.