Hi Sasha,
Thought I'd add my 2 cents worth for you to wake up to!
Good advice you've been given from others in this group btw.
Perhaps try and be fussier about being on time for your meds and get a pill cutter for more accurate dosages and take the same amount of levodopa in a day as you do for now only at a reduced dosage, try perhaps hourly.
I think you said you're on 100mg levodopa 2 hrly so try 50 mg hrly and experiment a little.
25 mg an hr may even be all you need for less fluctuations.
Go and buy a new bottle of levodopa too as like Ron said it may be the cause.
Make sure you check the batch number is different to what you have now.
The symptoms you mention sound like you're plain old off to me so maybe give it a go and as I often say we need to be captains of our own ship so experiment a bit with the above and good luck!