Is Spotting Instead Of Menstruation Normal?

Hi.....I am 29 yrs old, 5 feet, 67 kgs, got 2 kids. i've put on some weight recently, so my periods is irregular for the past 3-6 mths, i was asked to take Sysron-n tablets twice daily for three days, after stopping the pills got my periods but it wasn't proper, (usually its 5-7 days for me) but its was just spotting that happened for 2-3 days...is that normal? Please advice me on how to make my periods regular as before. very much worried.