Yes, it will get better...my son was in Kinder last year and he was sick every month from August through February...his attendance was awful. He even caught mono and was out weeks...three or four. (I got so many letters from the district telling me I would be prosecuted for his absences). They were all excused.
I had doctor's notes (in fact I knew all about my pediatrician's nurse's love life we saw him so much...and what concerts he was going to...and how the concerts were...etc). I felt like we lived in the pediatrician's office.
Besides strep throat, the three day mystery fever, and mono...my son kept getting this "runny nose/then it was bronchitis/then it was pneumonia, it kicked off severe asthma" thing that happened once a month as well...he seemed to never stop wheezing.
So, long story short we had him tested for allergies...he was highly allergic to dust mites...like over the top, huge reaction. They live in carpets/bedding/ and stuffed animals. Our house has NO carpet and he doesn't have many stuffed animals...I wash bedding weekly...HOWEVER his classroom had a huge ancient "reading rug" where the kids sat on a lot during the day. So he was reacting to the dust mites at school that started the runny nose that turned into the bronchitis kicked off the asthma and then we moved into the pediatrician's office for the following week.
Once he started on allergy medications...that he only takes while in school (he doesn't need them over the summer) he is fine. In fact he just got a perfect attendance award for the first nine weeks of school.
I almost just chalked all the sickness up to his first year in school...but was really glad my pediatrician suggested the allergy testing. So if your son has continued respiratory congestion that keeps occurring over and over...maybe it is an allergy to something in the classroom...my son's was...