Could i be pregnant

I’m almost 5 months PP and have been exclusively breastfeeding. I started bleeding Monday and thought it was my period. However it didn’t feel like my period. Per pregnancy I would get really bad cramps during my period. This one felt odd. It was heaving bleeding at first and no clots. Lasted about 4 days. I’ve also been feeling moody and really tired. I also feel tender boobs which I don’t usually feel even with breastfeeding. Today I took a test and it was really faint line. I’m very nervous because I’m not sure if I’m pregnant I have to wait until tomorrow to take another test. Please let me know if anybody has experience this.