Why do I feel so weak and tired?

I am 39 years old, I have 3 kids that are 8, 7 and 11 months. I just feel so tired and weak all the time. I tried taking multi vitamins but I didnt noctice much difference. I dont know why I feel like that. I thought maybe Im just tired because I have to run after 3 kids everyday but could it be not the only reason? Im posting it on Adrenal Fatigue Forum because I didnt find any other forums relating to fatigue...although I thought of the possibility of having the adrenal fatigue too but truth is I dont know what is it. I also feel weak...I am in bed a lot...I cant even imagine lifting weighs or going for a run, I feel like it could kill me. Any ideas what it maybe? I feel a lot older than 39 more like 70 lately... Tweet