Dont freak out. Switch the shoulder and DG locations so you have 4 spots if needed since you have been injecting frequently.
Good videos in first thread linked. Look up a map of nerves for shoulder, DG and quad sites. Shoulders / DG are good locations. Stay away from quads.
WRT L-Carnitine Never Ever do IV injection. You could try IM on the shoulders. Never tried the L-Carnitine injection for receptor sensitivity thing.