If you have a lot of D you really shouldn't be afraid of Immodium. Toxic megacolon is far-fetched at your point, dehydration is more likley especially when alcohol is involved
. I avoided Immodium for a long time but my doctor told me it was fine to take it and after using it to slow things down I really agree.
Last year I alternated between D and C but since getting my diet under control I never have C any more so Immodium-fear is gone. Try it, it's not a miracle worker but it is something you should have in your medicine cabinet and use as needed.