I just started taking doxycycline for possible lyme's 100mg twice...

I just started taking doxycycline for possible lyme's 100mg twice daily. I have to say I can't believe some of the things I'm reading here. It honestly makes me want to stop taking it. My doctor prescribed it for 21 days. I'm going away on vacation 15 days into taking this medication. Does anyone think it would be ok to stop this on the 15th day vs taking it til the 21st day. I really really don't want to have any problems while on vacation. Your help would be appreciated. Thanks