Hi My Periods That I Normally Get Are Very Heavy

Hi my periods that I normally get are very heavy and painful and last between 5 and 10 days - I have just come back off holiday and was meant to be due on whilst I was on holiday so I took some tablets my doctor gave me I stopped taking them the day I came back and came on 4 days later but this time my period was very light, still had cramps but wasn't as painful and only lasted three days, could this be to do with the tablets I took to prospone my period