Help!

My little fella turned 2 months old Friday! He has since been very lethargic. He just seems blah, he's got no appetite really, and he sleeps most of the day. When he isn't sleeping, he's fussing. He also had a BM that was pale yellow and was like slime. Like the slime you make with glue, borax, and water. I've never seen anything like it! There's no fever either! I expected the fuss the day after but not a full week almost. Any help? Advice? Anyone experience this with their LO?