Bactrim and Low Blood Sugar - Help Please

My endo prescribed an antiobiotic, Bactrim, for a uti. My first dose was last night. I took my basal Lantus of 28 units at 9p.m. I started the night high at 190 because of infection but only took 0.5u Humalog at 10:30pm. because my overnight basal needs have gotten out of whack lately - some nights I drop and some nights I go high - usually around midnight.

I woke up at 1:30a.m. this morning at 50!! That's a drop of 140 points in 3 hours. Thankful that I started out high or I would have been in real trouble. All day today I popped jelly beans to stay above 80 (not normal for me).

I'm a little slow to make the connection that the antibiotic causes low blood sugar - just hit me a few minutes ago and I looked it up online. It makes me angry that the endo didn't warn me - he of all people should have known.

Now I'm afraid to take my regular basal dose of 28 units of Lantus tonight. How much would you cut it back given the drop of 140 points last night? I'm thinking of eating something at bedtime to push up bg, which I hate to do, but I'm afraid to sleep. Then see what it drops tonight.

What would you do?