Body feels like it's made of lead :(

I'm 21 suffering with Depression, GAD and OCD. For about a week now I feel physically exhausted and unwell. My lower back is in bad crunching pain. I feel like I physically cannot get outta bed or stand up because I feel so tired. My mind feels "tired too" like I just don't have the energy to think or care. It's like I didn't sleep for a week even though I have. I get up and I just can't wait to go back to bed. Despite taking my lexapro 20mg everyday for 2 years I feel like my mental health is going downhill. I had the flu a couple weeks ago and I didn't feel as bad as I do now
When I'm outside I don't feel too bad or when I'm doing something but when I sit down or get a second to rest I just feel so drained to the point where I can't get up. My body feels like it's made of lead. I started taking multivitamins a few weeks ago but it's clear they aren't helping. I have headaches all the time and my body just aches all over. I only have the energy to eat and sleep

Definitely sounds like depression and anxiety. I go through the same as you and I have those (and OCD).

Especially the lower back hurting - sounds like tension.

Feeling like lead, as in just really heavy and weighted down? That's depression.

Sorry I don't have any advice, just saying I go through the same things and what the cause is.

Do you have a therapist? I'd suggest talking with one.