All kids get antsy, especially our kiddos. What has worked for us is allowing our Daughter to stand while doing homework, she would wander away, which we allowed as long as she came back to work on her schooling. She eventually grew out of the need to stand and could sit for longer and longer periods of time. No medications needed.
With our Son, we had a big exercise ball for him to roll on, sit and bounce with his bottom on, and smack with his hands on. He was also allowed to roam as long as he came back and tried.
Meltdowns can be greatly reduced when you discover what is causing them. Usually, it's a combination of things. *Our kids don't like to have sudden changes in their schedule, so letting them know ahead of time and reminding them a few times beforehand helps. ( You can even set a timer, and point to it.) *Sensory issues, such as bright lights in stores, sounds hurting their ears, clothes they don't like the feel of, can all trigger a meltdown. Gunrange earmuffs work great for hearing sensitivities, so do special earplugs for people with sensory issues. Wearing sunglasses can help shield them from light. Smells can be triggering as well, with us we had to stop going into certain craft stores that had scented pinecones, etc... To help with not liking to wear things they need to wear, (such as shoes, gloves, hats...) try desensitizing the specific area by gently but firmly pressing, or squeezing the area before putting the clothing on. (This also works for toothbrushing... press/rub cheeks, lips, outside of mouth, and allow kiddo to chew something chewie T or gum, right before brushing.
*If a child is having a hard time with meltdowns, it can also mean they aren't feeling good. Toothache, headache, stomachache, etc...
*Difficulty communicating can be a big factor in meltdown. Using a tablet with an app to talk, or using pictures to point to, or PEC cards which can be found and printed off of the internet for free work great. I also recommend reading the book "More Than Words," by Fern Sussman. To help your kiddo learn to communicate. It's very well written and easy to understand what she's saying. Also "Baby Bumble Bee" and "Signing Time" Makes great videos for the kiddos to watch and learn new words and helps with communicating.
I hope some of this has helped. <3 You've got this! :) Things will get better.

Too early. Brain is still developing, and you need meds as last resort.

I can see why you're uneasy about giving a 4-year-old medications. I guess it would depend on what kind the doctor wants to prescribe. A lot of these medications can wait until the child is older to see if they really need them or not.

We never used medication. It was a time when the meltdowns were severe and we used CBD. It got us over the hump. Meltdowns are maybe once a year now. It gets better. Hang in there mom. A lot of times all they want to do is drug our boys up. If he is intolerable and all forms of behavioral approaches have been exhausted OR if he is harming himself or others... by all means but if he is just a rough and tumble boy I would not. You may not be able to have the ideal social life at this time but sometimes these are the sacrifices that have to be made.

@A MyAutismTeam Member, "Another thing to consider is that there are no studies done on medications for children under 7 yrs. old to determine safety & efficacy." Could you provide a legit source on that? I have a hard time believing that one.

My daughter has been on guanfacine since she was 4 or 5. She's 11 now. With a doctor's prescription and oversight it has worked so well that other people could see the improvement so it's not just our opinion. You can try meds and drop them if they they make things worse but I would never dismiss them oout of hand.