Which Radio Shack amplified indoor antenna do you have? The model number.
If its the 1892 that looks like a flying saucer, that is about the best indoor antenna you can get, and if its not doing the trick then you will have to find an attic or outdoor antenna solution. (BTW, you can run an amplified indoor antenna from inside the attic to get better elevation and perhaps signal strength).
If not, get one, that you can return (Radio Shack has a good return policy) and try it out.
There are a couple of other alternatives, but these are harder to find locally, for easier return. Terk HDTVa, and the Quantum FX ANT-102(which is a lot like the old RS 1880).
Also before you go this route, your real problem seems to be VHF High and the above recommended antennas really dont give you any advantage on VHF High over basic Amplified Rabbit Ears & Loops. As their VHF sections are identical Amplified Rabbit Ears.
Try this with your Amplified Rabbit Ears. Pull out each telescoping section to 28 to 32 inches on each side and try them folded out horizontal and inline with the loop and then move the whole antenna perpendicular to the towers. (Note use equal dimensions 28+28 or 32+32) You can also experiment with angling the telescoping VHF dipole rabbit ears in a V towards the transmission towers at 60ish degrees on the compass dial from 30 to 60 degrees in 15 degree intervals....moving both ears together.
Other than that, get an length of coax (12 to 25 feet or 50 if that is what you have to hand) and a barrel F to F connector coupler, and try your antenna in different locations. (Hanging upside down from the ceiling in front of the window to the NorthEast (60ish degrees) is a popular and good spot for out of the way permanent mounting location....or just in the window sill if you arent that radical

) The extra length of coax will give you some space to try the antenna out in different locations looking for a sweet spot. Put it on the problem channel Fox and walk around with it over by the window, here and there....setting it different places. This can help out immensely and could solve most of your problems.
Do you have a brick, stucco, masory, concrete or metal siding building where the TV is located?
Report back your findings.