I had a small lump on my breast. They're lumpy anyway so I kept my eye on it but when I felt it was persistent I went to the GP and got a 2 week wait.
No matter what I knew to reassure myself - low risk, not long finished breastfeeding, lumpy breasts anyway, little family history, young... I went out of my mind.
I was worried, and I couldn't rationalise it away.
So I wont tell you not to worry, and that at that young age he's likely to be ok. It won't matter, you'll worry anyway.
So try a bit if self care instead, allow yourself 2 times a day where you can worry to your hearts content. E.g.,10am after school run and 8pm before bed. Allow yourself an hour of googling and panicking and answering questions you've had all day. If you worry just say "I'll save that for 8pm"
Make sure you eat well, relax with a bath or a movie, the gym, a takeaway or a cup of tea regularly - whatever you normally do to find some escape.
Next week will come whether you are ready or not, distressed or not so just ride out the wave that gets you there 