Help with possible seizure in toddler

Hi folks. This is an amazing forum. Lots of great caring people and good information. I'm a 37yo medic professional (respiratory therapist) and my wife is also a professional in the health care field. But we have minimal experience with seizures. I'm not looking for definitive information - no substitute for a physician's diagnosis. Please understand that. I'm just a loving daddy who is worried about his 18mo baby boy, and am looking for info while waiting his neuro appointment. My 18mo has been doing this thing where he grabs the right side of his head and SCREAMS while looking us in the face. It has occurred maybe 8x in the last 3monts. Each incident lasts no longer than 3-5sec max. No symptoms leading up to it. About half the time he appears tired and wants held immediately following it. Mind you, it typically occurs while he's with his mommy and I'm in another room, and while she's looking away when it starts. No repetitive movements, no convulsions, nothing else that would make it simpler for us. Don't get me wrong, I'm grateful it's not glaringly obvious, as we worry about tumors, etc, that could cause this. Oh and it's never happened while asleep. I am glad to answer questions and am sorry if this is a waste of your time. He's our only child and he's the center of our universe every second of every day. Being in health care, we only see the rare bad stories. So I'm just grasping at straws as the symptoms don't seem to match the online descriptions. Just trying get to gather as much info as possible. Just tell me if I'm out of line or unwelcome in this community with my vague questions. I'll understand. But thank you in advance for any information anybody may be kind enough to share. God bless.