It`s quite apparent that the nonhealing ulcer(you have`nt mentioned the site) has been diagnosed of tubercular etiology hence anti tb treatment has been started.
The four drugs used in tb treatment in initial phase are:
Rimactazid 6oo which has 2 drugs-INH
PZA dose is 1500 to 2000 mgm depending on your body weight
4th drug is Etambutol 1000 to 1200 mgm.
I do not know why leon 750 has been started instead of ethambutol
as it is normally reserved for drug resistant tb. Your doctor must surely be having a reason for it.
In tb 10 to 15 days is too early to expect any appreciable improvement. You have to give it time. However possibility of drug resistant tb has to always kept in mind.