OK, I'm not even going to get into the Benadryl thing. I understand the temptation, but I think a quick phone call to a pharmacist will give you all the information you need about it being a central nervous system depressant to permanently discourage the use of Benadryl in this situation.
I'm copying and pasting some stuff that worked for my older daughter, who is about as high needs as they come.
My personal belief is that you may be going through some exhaustion/ crankiness due to sleep deprivation. A few decent nights sleep may make a huge difference. My dh took over the night wakings for my older daughter after Rosie was born, and that made my life a lot easier. He would just take Gracie out for long walks in our BOB jogging stroller. She loved the middle of the night walks, and the stroller put her right to sleep.
Yeah, sadly, for some kids waking up that much is normal. My first dd woke up that much and she didn't start sleeping through the night on most nights until she was two and a half years old.
The thing that helped us the most to reduce the nightwakings (this did not eliminate them, but it cut them down by almost two thirds) was to make sure that she was very comfortable. Here is what we did:
1. A big snack right before bed (followed by the last day's toothbrushing, of course). This was something filling and easy to digest, and required us to move her biggest meal of the day to 4pm with smaller portions at dinner. The snack was usually Earth's Best Plums, Bananas and Rice or a banana or applesauce or a slice of whole wheat bread. Bland and filling.
2. We kept a sippy cup of ice water by the bed and always offered that first before nursing. Yes, she fussed at first, but this cut way down on the length of nursing as well as the number of wakings.
3. Temperature: a) Cool air in the room, even if it sent our AC bill through the roof.
b) Warm, soft pajamas with socks on her feet. The combination of soft warm pajamas (we love Hanna Andersson baby zippers http://www.hannaandersson.com
) and cool air made a big difference.
4. Put all the dogs in the garage so their barking would not wake her up. If there is some noise that is waking your child up, figure out what it is and reduce or eliminate or mask it.
5. In our family, dh was a major insomniac and was a big part of the problem because he woke up off and on all night long and then crept (not nearly as quietly as he imagined) around the house, in and out of the bed, etc., repeatedly waking her up. He broke this habit when he realized it was driving everyone else crazy. Now he sleeps better than ever.
6. Soft, soft sheets and blankets. We use one hundred percent cotton jersey knit sheets, which feel like an old soft Tshirt.
7. Plenty of room on the bed. In our case, we have a kingsized mattress on the floor with a single mattress on the floor right next to it. That way, Gracie gets to snuggle up to her parents but she has her own comfortable space.
8. If, by some fluke, she takes a nap in the afternoon, I would wake her up if the nap went past 4pm, even if that meant she was cranky for the rest of the day. If we didn't do that, she would be up during the night, and then the horrible cycle would continue for a week. If you are working during the day, your child's care provider might be enjoying a late afternoon nap for your child that is wreaking havoc on your nighttime routine.
That's all I can think of right now. I think you might be amazed how big a difference this stuff makes, almost overnight, especially the snack/sippy cup thing. A lot of my children's night nursing was due to hunger and thirst. My mother said that in the sixties with her kids, there was a saying "feed them, don't wean them." I have to say that it seems to work.