You may have some imbalances from pregnancy- I know I do! I will be heading to physical therapy after a month or so. Also, make sure you use good form when lifting and moving. After my first pregnancy I had a lot of hip and back pain due to poor posture and form when lifting things like the car seat and the baby
I’m still taking my prenatals and I notice when I forget to take them I feel achy and sore. Def talk with your doc about it.. could be more than a nutrition thing
I know I personally get achy knees/legs when I don’t get enough sleep 😅 that and “nursing neck” which is the tightness/soreness/tension in my neck, shoulders, and upper back from leaving over and nursing all the time. Maybe try some magnesium supplements and/or lotion for your achy joints! I’ve heard it can help a lot