My Son Had His 2 Month Vaccines 4 Weeks Ago

My son had his 2 month vaccines 4 weeks ago and has had a fever between 99-100 on and off since then. We think he may be teething as he is drooling constantly and chewing anything he can. We had bloodwork done and his white blood cells were fine but had a platelet count of 662. Why would he have high platelet count?