Scam callers have and do spoof other phone numbers with their auto-dialers when attempting to hide their true identity.
You may have been the unlucky victim of this type of situation, a scammer has spoofed your phone number.
See:
Greenfield Park resident's phone number used in scam calls - Montreal - CBC News
This may explain why you are getting calls from random people asking why you called them, when you log shows nothing.
However, to double check, look over the call records from your cell carrier statement or online account management, as they will show calls too and from your number, even if your device logs show nothing.
If the outbound calls show up there and are time stamped at times when you know for certain that your device was not in use, then there may be a more serious issue such as someone has access to your account or has "cloned" your account to another device.
If this is the case, contact your carrier ASAP for assistance.