Do avoid eating food on the street in India. Especially be careful with the drinking water. Most people who travel to India especially if travelling for long can get a bout of Diarreha. The cause is usually ameoba infections. The best treatment is a Drug called Ciplox-TZ that is manufactured by a company called Cipla. It is a combination of Ciprofloxacin 500mg plus Tinidazole 600mg. There are other manufacturers too. This drug must be taken twice a day for 5 to 7 days. The diarreha will stop within a day or two but continue for atleast 5 days if not more. Usually if you stop in between chances are of a recurrence.
Most medicines in India are much cheaper upto 10 times less than Europe or the US. Try to buy medicines from a large store in Big cities. Check on the name of the Manufacturer. In some cases in small towns one may buy duplicate medicine. Generally speaking the quality of medicines in India is excellent. Most travellers who complain usually do not go to good Doctors and end up with incorrect Diagnoses.
Clothing is India is also much cheaper especially cottons. One can simply buy stuff in India instead of carrying it and leave it behind before departure.