Sticking points in the pedal stroke During a stroke, I encounter one or two (not always in the same pedal position) where the resistance is high. If I spin the crank freely (on the bike, wheel off ground), it will quickly come to a stop at one of these points. So, part of the stroke is fine. At these points, spinning the cranks backwards, the chain seem to collapse at the top. I feel like maybe the back cassette isn't spinning as free as it should.
Does anyone have any idea of what this could be?
I feel I take good care of my bike. Cleaning it from dirt about once per week and degreasing/greasing the chain typically twice per month.
I'm fairly new to bike repairs so any help and pointers are appreciated.  Note:  The bike is fairly new; only about a month old. I've ridden about 2500 km.
Either the rear wheel or the crank bearings are binding at some point in their revolution, or (or possibly there's something going on with the chain). The first thing to do is track down where the problem is.
Check first for obvious stuff, like is the rear wheel out of true and rubbing the brake blocks?
The next easiest thing to do first is take the rear wheel out, remove the quick release skewer and check the bearings. Turn the axle with you fingers, does the axle have a tight spot, do you feel excessive resistance or 'notchiness'? Push and pull the axle about to check for play, if you can feel the axle moving more than a tiny bit there is excessive play.
If the wheel bearings are is OK, check the crank. Most front derailleur cages have a small screw that allow them to be opened and the chain removed. Get the chain out of the cage and off the chainrings (it's awkward but possible). Spin the cranks by hand, again checking for a tight spot, excessive resistance, 'notchiness' and play.
The wheel is the problem fixing it depends on the type of bearings. Some hubs have 'serviceable' bearings that can be disassembled, some have pressed in cartridge bearings. If the crank is the issue, a new bottom bracket is required.