How?!?!

I moved in September.. my daughter no longer used the crib so I put it up(she used it for 3months) when I moved. I put everything together in one spot. Went to put it together as I’m 33 weeks and want it up now. So we get the frame together. I’m like okay where’s the mattress. We looked everywhere. No mattresses. My brother bought my old house so I asked him if I left it there because he would of stored it for me or said hey you forgot your crib mattress and not just throw it away..I know it come in to this house, I’m the one who put it right next to the frame. I tore my house top to bottom, no crib mattress. Like it’s completely gone. How does a crib mattress go missing? When we did move, the neighbors next to me had yard sale everyday and said new stuff everyday. I didn’t lock my doors when I left but why would they take the crib mattress and not the 6 smart screen TVs that all new beside one, the 3 Xbox ones, the game laptop or the Switch. Those would be better to take so I don’t think they would. But it wasn’t the first thing that come up missing, our coffee pot, pans, and few other random objects went missing. Ugh 😫. The crib mattress I had come from buy buy baby and that’s 3hour drive and I’m not allowed to drive more than 1.5hours away as I’m high risk for premature labor and they don’t want me going to far. So now I don’t know where to buy a crib mattress. We only have Walmart and Meijer here that sells baby stuff..