This is very common among people with young children. As I’m sure you know, these are all completely different infections with no cross-immunity between them.
We’ve had a few threads like this here over the years (like here and here), and that advice generally stands. Based on what you describe here, the probability that a medical evaluation will turn something up is low. Aside from this, you are already doing most of the relevant lifestyle behaviors. In addition, hygiene and handwashing are beneficial, while immunization lowers the risk of symptomatic infections (and tends to lower the severity of breakthrough infections, if acquired).
Lastly, recent evidence has found that intranasal Azelastine spray lowers the risk of common viral infections, including common colds (often due to rhinoviruses) and covid.