Describe a funny sensation in your body which doesn't really have a proper word.

That feeling you get when you've been working for something for days, weeks, maybe even months, and you finally finish or accomplish the task. That feeling of excitement and relief.
It makes me think of my dad, who in his spare time decided he was going to build his own Stirling engine. I still remember him spending days on end in the garage. He'd spend so long in there sometimes that mom made me go check on him, or remind him that he still had to eat dinner. Of course, this was before we had high speed internet, so we didn't have you tube videos to help us out. It must have been at least 3 weeks of this, including Sundays. When he finally finished it, he carried his engine into the living room, set it on the coffee table, and just let it run, until it burned all of its fuel.
(This obviously isn't the engine he built, but it is a Stirling engine, and it might give you an idea of what it looks like.)

weird tingly feeling from my head which goes down my spine at random times and for seemingly no reason, does this just happen to me?

the swelling of happiness when you see the person you love and it feels like you're going to explode and you literally feel more whole

also

that feeling when you smoke too much pot and it feels like there's a ball in the back of your throat that you can't get rid of.....