Feeling tired and weak almost all the time

Hello. It's been a very long time that I'm feeling tired almost all the time, right when I wake up I feel like my eyes are tired and it wasn't always like that, when I used to sleep good I woke up fresh and strong but now I wake up tired, and I'm kinda tired through all the day and feel weak. I also have this uncomfortable feelings in my legs sometimes - I don't know how to explain this but sometimes when I lay down I feel an uncomfortable feeling that make me want to move my legs, and it's hard for me to do an activity with my legs. It's not like I can't walk or run or something but not at the same level that I used to, they get tired much faster, and most importantly it's even been hard for me to stand still for a long time, I feel like I have to sit down after a pretty short time compared to my abilities in the past. Basically I feel that they became weak, like they're 'sleeping' or something. I think it got something to do with my tiredness and weakness.

Based on some articles I've read on the internet I feel like it got something to do with lack of vitamins, maybe lack of iron (because of my tiredness and weakness and the uncomfortable feeling in my legs).

I know that the best solution right now would be just seeing a doctor and I probably will but I rather avoid it if I can, maybe it's the kind of things you can cure by yourself. 

So what do you think? What it is? Thanks in advance. 

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