The scale

Can someone explain my weight gain? I have been breastfeeding since May( my baby is 2 months) and I reached down to my original weight which is 120 in the beginning of July. Fast forward to now I’m 124 and not sure why. In June/July I wasn’t worrying about what I ate and I barely went to the gym. Towards the end of July my milk supply decreased and I was trying to eat healthier plus doing my old workouts. I’m drinking lots of more water and eating good foods but the scale keeps going up I’m not sure if it’s because I got my period back or another reason maybe someone can help me