First of all, congratulations on your baby! That's very exciting.
Second, I'm not sure I can help much, because my anxiety is more general than specifically health-related, but I will say it did ramp up A LOT after I had my children. My first is 4.5 now, and according to my husband, I haven't been "myself" anxiety-wise since he was born. It's like I never recovered after having him. Then I got pregnant with my second, who is now 5 mos, and I totally fell apart.
Like I said, mine is more general, but it does definitely include some health anxiety. It's more fluid and all-encompassing though.
Are you prone to anxiety anyway? You mention that the birth of your son has triggered your health anxiety - have you ever been treated for anxiety before? I know there's a lot of talk out there about post-partum depression, but for people who are prone to anxiety anyway, PPD can manifest as anxiety rather than traditional depression symptoms. Does that make sense? I don't want to be the one who automatically jumps on the PPD train, but it's something to consider. I've been on meds since the day after my baby was born - it's my first time trying meds, and it's a very low dose, and I really think it helped take the edge off the post-partum tornado of emotions so I'm able to cope with things and just life in general. I"m also seeing a therapist for the first time, and that is helping,too. I found someone who doesn't mind that I bring the baby to my appointments (I go when my older child is in preschool), so that has helped facilitate the process, as logistics are a big trigger for my anxiety.
Good luck! This is a trying time in your life under the best of circumstances. Add in anxiety on top of it all, and it can be overwhelming. But you're not alone, take care.