If you are worried about it go - try to keep calm as it is more likely she picks up on your nerves than any memory at 13 weeks. Chances are it is just bruised, especially if she is weight bearing , but have known toddlers fracture arms where it has not been an obvious problem for a day or two. Their bones are pretty soft but an awkward fall can still cause damage.
dd tipped her 3 wheeler and caught her leg underneath last year as it fell on its side. It didn't swell much but she was obviously in pain and bruised. Wouldn't walk on it, even the following morning. Had just made her an appointment at emergency dr the next day (at a really awkward time) when ran into a neighbour with her dd - mine suddenly came back to life and started racing around. Cancelled it but did go to own dr the next day, by which time she still limped a bit Dr didn't think it was fractured but if it troubled her further would arrange an xray. Within a few days it was forgotten about and she was back to normal.
Hope all is well