the Allez was a good start but every bike is different and it is great that you are going to try different bikes! personally, I think you will find a more comfortable bike than the Allez, once you start looking -- you will be amazed!

as for your shoulders/neck, sounds like nerves because hard to imagine you strained anything doing loops and figure 8's around a parking lot ... tension of new bike and new position can be very scary!

whatever bike you do, please get a FIT!!! per your description, I seem to be the same height as you, but that does not mean you and I would necessarily ride the same bike EXACTLY ... we could have different femurs causing our legs to be higher/shorter, different torso lengths, arm lenghts, and flexibility issues ... so it is real important to get a fit before final purchase!

fyi ... in general, I like a road bike with a toptube length between 52cm-53cm, using a stem or 90 or 100 with a slight 6 degree rise ... this may be a good starting range for you, BUT THEN AGAIN (please see above paragraph)

Good luck!