Toddler losing weight

Tess • Nari Lyn 11/13/17🎀Emma Rose 3/17/19🎀Pierce James 9/28/20

Is anyone else’s toddler losing weight to the point where their pants , that originally fit, falls off for example?

My daughter is 2.5 years old and she was born very small (4.11lb) and she JUST hit 21-22lb recently but now her 2T clothes are falling off and she fits in 18 months. She hasn’t seen the doctor recently and I will be making an appointment soon, but is anyone else in the same boat?