Doxycycline Hyclate and skin discoloration

I was on Minocycline (a cousin to Doxycycline Hyclate) for years. I’m not sure how long exactly as I didn’t write down the date that I started, but I believe I have been on it around 3-4+ years. Well I went to a dermatologist and he instantly looked at the outer area of my arms (just above the elbow) and recognized I am suffering from skin discoloration, and prescribed Doxycycline, and told me to stop taking Minocycline right away. I also have this blue-gray skin discoloration on my back near my shoulder blades. I took my Minocycline for the next two weeks till the Doxycycline came in then stopped the minocycline, and started Doxycycline on Sunday. I take a 100mg pill twice daily with a meal, and thus far have had no issues. Keep in mind that I have been on Minocycline for the past 4 years or so and maybe I’ve been suffering similar side effects on that drug, thus I would be unable to see the difference with Minocycline’s cousin Doxycycline. I am pretty sure the first year or two that I was on Minocycline I was depressed (other things in life may have contributed to this depression, but now that I see all of these people saying they have had mood swings, I must state that I have had many more mood swings in recent years then I ever remember before being on these meds). I have also been extremely sleepy the past few years. I used to NEVER be able to fall asleep in public, but (I believe about the same time I started Minocycline) I gained the ability to sleep anywhere. Now I mean, anywhere. I can sleep even after I get anywhere between 6 and 14 hours of sleep. I have had approx 7-9 hours of sleep on average for the past 6 months, yet am always tired. I can’t remember the last time I haven’t been sleepy, and have had many doctor visits to attempt to discover the reason for this, but hadn’t read the side effects of Minocycline. I’ve still been pretty sleepy since Sunday, but I’ll hope that this Doxycycline isn’t as bad. Anyone else have a similar issue, where you used to be awake, but now you are always sleepy (wake up in the mornings a bit dizzy and confused), and have a hard time concentrating on one thing at a time?