Firstly welcome.

You say it shakes at high speeds.

90% of the time if you feel a vibration at 50mph+ while driving its a tire issue, balance needed or something wrong with the tire.

If you feel the vibration while braking only it is usually a warped rotor.

Since you say you just had a strut replaced but no alignment I would say the alignment was off just enough to wear the tire and cause the vibration. I have done brake jobs plenty of times and not replaced/turned the rotors, usually just results in some noise and faster wear on the pads. Very rarely does it cause a warped rotor, but it could be possible.

I would seek a tire shop and have the tires checked and balanced first.

If it still does it, consider checking the brakes again.