What Causes Nausea And Fatigue After Discontinuing Birth Control Pills?

ok i was taken birth control pills faithfully jan feb march and april but in april i got a light period for three days 4/23 24 25 and it was light not normal at all so i finished the pack of pills and did not continue them at all for may then may 4th i got a bleeding like a period it lasted for about 4-5 days then i started getting sick nausea fatigue gas heart burns i guess those are symptoms id get from going off pill but anyhow i started gaining weight and when i started working out my body is just not into it i havent taken another pregnancy test but what does this sound like to u??