I don’t know what to do 😢

I noticed a couple of days ago that my 2yo daughter was touching her private in what I thought was kinda sexual but I thought no Im just being sick minded well the next day she was im her room so I left her for a lil, while I made her bro a bottle when I got back she was like masterbating & I was shocked to say the least I told her to stop Ive never done anything sexual in front of her at all she is a toddler Idk what to think Ive always been with her I only had her babysat by my SIl when I gave birth!? Idk what to do please any advice would help is this normal!? 😞 & yeah I tried to check her private area & it looked normal to me & yeah Im going to a Doctor ASAP I just want opinions Idk what to think Im not telling her dad Im taking her because you never know I trust nobody at this point 😡 How can a toddler just randomly do that?