What Causes Pain And Weakness In The Legs?

Various parts of my legs hurt and my legs feel tired/weak. It s hard walking, especially up the stairs, and it feels like they will give out. There s pain in my shins, calfs, thighs, and hamstrings. I also have pain in my knees and now I got hip pain. Most of my symptoms started yesterday and made it hard for me to sleep. I didn t do any exercising yesterday. All I did was lean over something to do something and my legs started hurting. They felt as if I exercise by running up multiple stairs with a heavy backpack but not quite. I had joint problems in the past and used to wear something for my knees. And some back and shoulder pain. I m a 20 year old male. I m just curious as to why my legs hurt and why they feel tired. I m not sure if I strained a muscle or several, or if it is something else, like fibromyalgia, tendinitis, etc. Nene azu Accra Ghana