Why is my 125 breaking spark plugs?

I got a 125 not so long back it wouldn't start one time so I changed the spark plug after doing every other test under the sun and it started easily with a new plug.. then 2 days ago it started revving slightly higher intermittently and then just cut out as I went to take it for a ride.. I suspect it's the spark plug again (last time I found the spark plug to be sparking against the plug wall not the gap so yeah) anyone know?? It's been about 6 weeks since I changed the plug and only ridden it twice other than that there's 600 miles on the engine?? Could it be the spark plug coil??? I don't really wanna buy another oem coil if that's the case id rather get a better one.. but does that cause intermittent high revving and 'crackling '??