wellcome to health care magic.
firstly when actually did this happen.
Secondly what is the substance that was consumed.now if its a toilet cleaner then a gastric lavage has to be done at the first presentation to emergency room.
Now if its acid then no gastric lavage is done.ulcer is a common complication since the acid will errode the epithelium.the time to completely get cure is difficult to predict like this.the ulcer has to be treated with antacid
group of drugs and also with antibiotic to prevent infection.secondly the patient has to be maintained on parenteral nutrition till the ulcer has healed.for all this pt has to be kept admitted.from your question it is not clear wat treatment has been done or what is the progress.