One of the reported side effects of Botox in large dosage is flu-like symptoms. I would consult with an internist to see if your flu-like symptoms are a result of the Botox injections or a virus or bacterial infection.
There are very rare cases reported of a flu-like illness about three months in duration following a Botox treatment, but it was usually a very big Botox treatment with more units than the average cosmetic patient gets. For example, if you were having all your wrinkles treated the same day as your tension headache.
I would not panic, and have faith that it is more likely what you're experiencing is just a regular cold/flu, sinus infection. In addition, it does sound like you got a more common side effect of the eyelid droop. That is bad luck, and should resolve faster with the eye drops your MD prescribed. The eyelid droop is thought to occur from Botox leaking down into the supraorbital foramen and affecting the nerve that innervates the upper eyelid muscle. This is more likely to occur if the injection was a tad too low on your brow, or if Botox was inadvertently massaged into the foramen. To avoid this, I take care when I inject to stay well above the foramen (which is easily palpable in most people) and I apply pressure after the injection in an upward motion, away from the foramen.
Anyway, I hope you're feeling better soon, and that you have a better experience with Botox, as so many people do, next time.
There are two things I am certain of: the first is that none of your symptoms are due to the Botox (I'll come back to the droopy eye). Stop reading misinformation on the internet. You probably have some sort of viral or bacterial infection unrelated to your treatment. I would have to see you to know what exactly your droopy eye is about. If you actually had your forehead injected and not your glabella (frown lines), it would be very unusual to have a droopy eyelid as a complication. More common would be to have a slightly droopy eyebrow if you have a heavy forehead/brow region. This will resolve over time. I'd suggest you get future treatments with a board certified dermatologist to minimize the risk of this kind of complication.