Weed causing feelings of depression?

i use marijuana very rarely and it seems whenever i do towards the end of the high and the start of the comedown i start to feel depressed even though i didnt feel any uplift in mood during the high? is it possible serotonin was being released without me feeling it and the depressive feelings i have are just my serotonin levels dropping further than normal with the comedown? i have depression issues normally could this be a factor into why i feel like that? the depression feelings always seem to be worse if i smoke alone.