Ignore the advice to complain.
New mums are anxious and it is usual for people to take their newborn to the GP. However, of course there will be times when a parent might be overly anxious and go very frequently. When that happens, a GP needs to gently voice it and reassure a parent about the issue even if it’s ongoing. It isn’t wrong to do this. Of course tone is everything g and we don’t know the tone used and neither does OP as she wasn’t there to hear it.
In reality, OP might well be hyper-sensitive....it’s not unusual with a newborn. Feeling worried is totally normal and going to the GP, sometimes several times for the same thing is fine. You do have to go with your instinct, but also it’s right to listen to the professional and it isn’t a personal attack to comment that someone has been very frequently wily for an issue...it might well be said to reassure them and try to help them not worry.
People are too quick to be critical of the GP.
Op, hopefully you feel a bit reassured about the rash now. If you feel worried about other things, absolutely contact the GP again....they did not say (according to your report) that you are a nuisance or that you shouldn’t go to see them. They made a seemingly factually accurate comment that you have been in touch a number of times about this particular issue. It doesn’t sound like it was a critisicm of you at all. In fact as the comment was made to your DH, quite likely the GP made it as a comment to your DH and did not particularly intend it to be reported back. We don’t know the context, but perhaps the GP has seen you are pretty anxious and was making a comment about that to your DH...not as a criticism at all, but an observation. Or perhaps the GP was simply pointing out to your DH, in case he wasn’t aware that the baby has been brought in several times already about the rash. As the GP hadn’t seen DH before, he couldn’t assume DH knew what had passed. There are all kinds of possibilities and the comment was made in the context of an appointment with DH not Op and what GP might have said to OP directly might have differed a little.
Anyway, don’t dwell on this. Honestly it’s a nothing issue. You can build it into something bigger than it is and fret and worrry and decide you don’t like the GP or build a whole story of what the GP thinks of you, or just move on from it. Acknowledge you are tired and possibly a little sensitive which is entirely normal and carry on doing the great job you are caring for your DC.