Postpartum weakness?

recently got my tubes tied in may along with a c-section and I've been feeling very weak lately. My normal strength is gone I'll just be leaning over changing the baby and my arms start to shake and I'll be putting away things on a shelf where I need to raise my arms and they will start to ache and cramp. Even now typing on my phone my hands cramp up. Ive haven't been lazy or laying around I clean everyday and take care of my newborn twins...I'm

Very motivated but my body cannot keep up with me. My back always hurts and my bones ache. I just honestly feel like I've been slowly losing all of my strength...even my memory isn't as great as it was. Anyone have any idea why this is happening?

Also if it has any relevance my stomach is completely healed from the c-section but I still get dull achy pains below my belly button and to the left about 5 fingers and there is a lump there but it does not effect me in anyway pressing on the lump hurts but the lump itself does not hurt ! Then pain underneath my left ribcage that sometimes radiates over to the right especially if I turn the my back lower left upper left and right hurt. Also finding it harder and harder to focus as if all my senses and strength are getting weaker.