Its likely your boy is tired of the view he gets on the floor and wants to be up high where things are more interesting and he can get around faster on mommy-power. And he's probably ready to learn to crawl. Give him lots of tummy time and encouragement. Our girl was crawling at 5 months and cruising at 6 months, but I worked with her every day many times a day to help her strengthen her muscles.
I chalked all our kid's "angry" times up to Developmental Milestones. She'd get really crazy when she was working on some skill or figuring something out, even something small. I read up on it and just tried to stay on top of providing interesting things for her to explore, and interesting things for us to do, even if it was just walking out of the house and going to the park or going to the store to walk around. Also, it came to my attention that playing with other babies is important too, and we weren't doing that hardly at all. "Parallel Play" they call it.
Also, they get clingy on and off. It's a phase, and it passes, comes back, and passes again. We got a couple of types of baby carriers, and she enjoyed that (and still does at 1 year). A Bjorn (the sport model because it has better back support), and the Ergo (we picked one up cheap at a kids consignment shop) which can be worn on the front or back.