22 months must be the age for it! Posted something on a similar thread in 'behaviour' recently as my DS is doing the same. He too has always been an excellent eater who likes trying new things.
Essentially yes, try to chill out a bit. Toddlers this age are notoriously picky and have appetites that wax and wain for all kinds of reasons but mostly because they're either just not hungry or they want to exercise some control over what they eat and when and how they eat it. The hallmark of growing independence i think! It's always useful to try to put yourself in their situation: are you always hungry? Are you always hungry for the same thing at the same time every day? I know that what i like to eat one day doesn't appeal to me the next, but i am able to choose accordingly. It must be very frustrating to be a toddler with limited verbal communication skills!
With that in mind, offer a choice where possible - an apple or a banana? Toast or cereal? Even if your toddler doesn't have many words, most will be able to point and express either pleasure or disinterest by 22 months. You could also try a plateful of different brightly coloured finger foods so that your DS feels he has more choice over what he eats. I now regularly do a plate of olives, ham, cherry tomatoes, cheese, chicken, boiled egg and a few fingers of bread with dairylea for example. Currently DS will eat everything except the bread. But in a week's time i expect it to be something else. He went off toast - until i showed him that by taking a bite here and there you can make it look like a fish, a whale, a car, a boat etc.
I don't offer alternatives either or give him dessert if he doesn't touch his main. At the moment he'll eat maybe 2 meals a day - there's always one where he'll barely eat anything. I remove it calmly and get him down from the table. If he asks for a banana i say no and explain it's because he doesn't seem hungry. More often than not i'll give him a small healthy snack an hour or two after the meal he's missed (such as the banana he asked for earlier). The important thing is not to let him associate leaving his meal with immediately having a nice, sweet treat. He can have one when lunchtime is a distant memory. He's usually ready to eat the meal after the one he's missed.
It's all very normal and they'll get over it providing you don't force the issue and remain calm. I think sometimes it's probably boredom with the same foods too, so keep trying to offer new foods even if they don't eat it at first. One day they probably will. Until then they'll get all the calories they need and will eat when they're hungry. Toddlers don't grow as quickly as babies, so the decrease in appetite can sometime seem a lot more alarming than it actually is. If he's bright, alert, happy and developing otherwise normally, then he's getting all the nutrients he needs.