My name is***** have been a veterinarian for 11 years. I am sorry to hear that Lola is having issues.
For over the counter antihistamines, as long as she has not has issues with them in the past, she can have a 1/2 tablet of chlorpheniramine (2 mg) by mouth every 12-24 hours. This will cause many cats to drool excessively, but it is safer than the other human anithistamines. It does not need to be separated from the cyproheptadine specifically, but due to the drooling, I normally recommend giving them a couple hours apart.
The chlorpheniramine may help a little with itchiness, but will not prevent the allergic reactions from happening. You may want to look at the types of "other" foods she has been eating recently to see if there is a common ingredient, such as chicken, fish, or beef, that could be causing her problems.
Please let me know if you have any additional questions.
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