Breast tenderness on one side

Hi ladies!

Question...so I’ve had pain in my right breast for about a month now. It’s localized to one spot and feels like a bruise when I touch it. It’s towards the center of my chest, on the inner part of the breast. I have a two year old and I lift him all day, so I feel like I may have sprained something and the pain is radiating to that area. I have felt around for a lump and don’t feel anything. I don’t have any noticeable changes on the skin either. Has this happened to you before?