Knee pain at 15 weeks pregnant?!!! Please read

I’m 15 weeks pregnant and I’ve noticed my knees are hurting now and then, I noticed it more when getting up off the floor (I have a toddler) or if I’m walking up and down the stairs. I’m confused because surly this would be something I get when I’m bigger? Can someone help me understand if this is pregnancy related and why? If it keeps acting up I’ll have to tell work but I feel like they will laugh at me and not believe me because I’m so early in my pregnancy.