Tequin is a member of the fluoroquinolone family. These drugs have extensive
neurological effects. Some permanent.

The mechanism that they use to cause neuropathy is not understood at this
time. So knowing what to do to counter the damage is only guesswork.

Methyl B12 enables the conversion of serotonin to melatonin --melatonin is the sleep hormone. So it is possible you feel tired because of this.

Also you could try adding P5P (activated B6) and folate to your supplements, since B12 uses them too. They work as a team.

If high doses bother you, just stay at the 1000mcg range. Studies have shown that it works daily as well as monthly injections. Take one an empty stomach.

Some drugs that cause neuropathies, respond to l-carnitine and CoQ-10.
HIV drugs and chemo both damage mitochondria. So if the Tequin works that way--you could try to supplement with those. They are not harmful, but they are expensive. This would be an experiment on your part.
We have some posts about that on our Peripheral Neuropathy board.
Just search there and the posts will pop up.

There are forums and websites on the net about damage from these drugs.
You'll have to Google those yourself.

Some people with very low potassium react to B12 because B12 stimulates formation of blood cells...and potassium is robbed from the serum to build those. So you may need higher potassium for a while. That you should discuss with your doctor..because too much is as harmful as too little.