"I would really appreciate your view. I worry there is something wrong with my baby, or else he is just inexplicably unhappy. He is 5 months old and only happy if he is in his Baby Bjorn on a walk, or watching Baby Einstein videos. He can do any of the following -- look at his mobile, lie on his playmat, sit on my lap, or practice tummy time -- for about FIVE minutes before he starts to whine. He whines in his bouncy chair. He whines in his high chair. He whines sitting on anyone's lap. He nurses well, sometimes enjoys a little cereal or banana, and, thank goodness, sleeps extremely well (both naps and through the night). Is it normal that he seems so bored and/or grumpy all the time? He smiles, but doesn't laugh often. Do you think there is something wrong with him?"
Normal, and normal.
He's at that age at which he's figured out that there's all sorts of stuff to do in the world, and he can't do any of it. Let's face it--mobiles and playmats are really only so much fun (almost exactly five minutes of fun, truthfully) but then he needs to be where the action is. He's a man on the town, a guy with places to go. Only he can't move around to get at any of that action himself. So it makes him pissed off and whiny.
He zones out with Baby Einstein because everyone zones out when they watch TV (which is why JetBlue flights are always so pleasant--everyone's anesthetized with the TV so they don't harass the flight attendants). And he's happy when he's up in the Bjorn with you because then he's up! where the cool people are! and he can see things! and he's moving! But then you want to get something done so you put him on the playmat and that makes him cranky.
Eventually this will pass, because eventually he will be able to crawl, and then walk, and then run, and then drive, and he'll be in charge of his own motion. But for now, the more you can keep him up and in motion the happier he'll be. The Bjorn is probably killing your back by now, so I'd just bite the bullet and spend the money on an Ergo or wrap. You can put him on your back that way and he'll be happy while you just go about your normal day. The motion all helps the neural connections form in his brain. When you put him down, put him on his tummy, because the more time he spends on his tummy the more practice he gets with the building blocks of crawling, but don't expect that he'll like it.
Other options are to borrow a big dog and/or a 5-year-old to entertain him in this premobile phase. But that might end up being more work than you want.
Any reminiscences or ideas?