If you have a legitimate license for Windows 7, that was used to upgrade to Windows 10, you may run either a legally licensed copy of Windows 7, or an upgraded copy of Windows 10, on the machine in question but you may not dual boot because if you're using the Windows 7 license the Windows 10 license is not valid simultaneously because it was derived from the Windows 7 license (and the converse).
If you wish to go back to Windows 7 you can. If you later decide you want to install Windows 10, you can. But you may only be running one of these two on that machine that have a single license as their shared DNA, so to speak.
Were you to wish to dual boot you would either need to upgrade to Windows 10, set up for dual booting and buy a separate copy of Windows 7. [Or you could set up Windows 7, set up for dual booting, and buy a separate license for Windows 10.]
I've posted on this in the past, quoting chapter and verse from Microsoft back when Windows 10 was in its early days, on these very forums.
In the final analysis the writing is on the wall for Windows 7. I'd be far more inclined to do a from-scratch installation of Windows 10 and reload the backups of your user data and reinstall any programs you use than I would be to revert to Windows 7. There have been lots of issues with machines that have been upgraded from earlier versions of Windows, particularly if those machines were "well-used" prior to the upgrade, that disappear with a completely fresh installation of Windows 10. You can actually do this via the built-in "Reset this PC" feature with the "wipe machine" option (as opposed to the "keep my files option.") You might want to try a Reset with "Keep my files" and see if this solves the issues you've been having.
Edited by britechguy, 16 April 2017 - 09:25 PM.