I was an Optician for many years. A few things:
1. Make sure you are only using the reading glasses for things closer than arms' length. Anything more than 23 inches away max is too far.
2. Try not to look up, at a distance while wearing the glasses. That is, don't look around the room or at other people through the reading glasses. This will cause headaches and eye strain, because your eyes are trying to adjust to an improper distance. Either slide them down your nose and look over them, or take them off when looking up from a book or close work.
3. Go back to the optician and have them adjust your glasses. They should never slide off your face. It's a simple adjustment and free, but don't do it yourself.
4. Are the distance glasses bothering you too? How do they feel? Do they feel tight on your head? If they are too tight, this can cause headaches.
5. You shouldn't be wearing the reading glasses to work on the floor. That's too distant. If you feel the need for improved vision at this distance, then ask your Optician about "intermittent" length glasses. It's slightly weaker than a reading prescription and meant for tasks just beyond the recommended reading distance.
Hope this helps.