This can be some allergies or your body reacting to progesterone differently this time. I hope you feel better soon or even better: I hope bfp cures all ills!!!!!
Yes its a natural cycle..still feeling like crap when I woke up this morning..ugh! lol
Was this a natural cycle? They say you can't feel symptoms until after implantation, which is 6-10 DPO. Because until then you do not produce HCG which make you feel "bleeeehhh" I have felt that way before though - multiple times. I remember because DH used to say "Why are you getting a cold/sick the one week when we could do without it." So just hand in there a few more days. Fingers crossed something is cooking :)
I felt the same way this cycle it started at 4DPO! I laid around a lot because I didn't have any energy. I don't know what it is but I can say I understand.