A horrible, no good day

Today is one of the hardest days we've had since the boys came home. The have both been running low grade fevers for the past few days. We assumed it was teething since neither of them have shown any other symptoms of being sick. This morning, Riley woke up and had a fever of 103.6. I gave him tylenol right away and had him sit on my lap with a cool washcloth on his head, while we waited for the pediatricians office to open. When I called, they wanted me to bring him right in. I made the appointment for both Riley and Addison since I was already going to be there and Addison had been running a fever also.
I assumed it would be something simple like ear infections. The doctor seems to think that they have roseola. It's a virus that shows no symptoms except a fever (that can go rather high) for 3-5 days and then they break out in a rash. We were sent home with instructions to just be sure we keep the fevers down and to come back if they still have a fever on Wednesday.
So, at about 3pm today, I was sitting on the floor with my legs straight out on the floor. I was holding Riley while Addison climbed back and forth, over my legs. He did a face plant (like he always does when he climbs over things) and just stayed there. At first I thought he was playing but after a few seconds, he hadn't moved. I picked him up to find that his whole body was stiff and his eyes were rolling back into his head. He didn't respond to me at all so I laid him on the loveseat and just tried to get him to regain consciousness. After about 1 minute, I called 911. I was frantic and the poor operator had trouble understanding me at first. He dispatched an ambulance (which luckily is less than 2 miles from my house) and by the time the ambulance got here, he was starting to move his limbs and babble. The medics said it was likely a febrile seizure and asked me to call the pediatrician to see if he should be transported to the ER or if they wanted me to bring him to the office. The ped. instructed him to be taken to the hospital to be checked out. He was stable and acting normal and I loaded him into the carseat and handed him to the medics who took him to the ER. I followed the ambulance with Riley. He had blood drawn to check his CBC and they did a urinalysis which came back clean so the ER doc. agreed that it was a febrile seizure. When he got the the ER, his temp was 101. I had given him a dose of tylenol just before he left.
I hadn't given Addison any medicine today since his temp was under 101 all day. When we were at the doctor, his temp was only 99 so I thought since he was acting just fine, I would give him a break from medicine.
He's fine now. He's been sleeping most of the evening and he ate a bunch of food. Hopefully, this virus comes to an end soon and I can not worry about this happening again.