Low Energy Equals Low Emotions

The last few days I have been fatigued and what comes with that are emotional lows. I've been feeling a bit invisible lately in the social scene here.  I've received an afterthought invitation a couple times in a row fueled my fear of being rather friendless. Not true, I know, but still I don't have my go-to friends, I pop into other people's circles when invited and sometimes I'm invited as the event is starting...a shitty invite indeed.
I have my EA friend and my E friend here and that should be enough. And mostly it is, I'm fine with flitting about and sometimes being part of groups. But when I'm tired, I'm down and my perspective is down. I see the worst.
I'm starting to come out of my fatigue, I think, and can put into a better perspective on my social life. One, it is hard to make new friends in a new place. That is clear and the biggest factor. Two, this is exasperated by the fact I live in Egypt and work often defined the pool of potential friends because of language, culture and schedules. Third, there is an even smaller pool who are in my age range of even 8 years either direction. Fourth, I'm admin and most of my options are teachers.
Writing that out and defining it helped. And that my birthday was yesterday helped.  Facebook messages and surprise visit from my best friend helped. EA pushing me to celebrate my birthday helped. (She know my sadness around my birthday) thank you EA! Planning vacations with other, now far away friends helped. Convincing myself in due time I will find my go-to friends helped.
What is causing the fatigue that leads me to these dark emotional places? That will remain to be seen. I would like to be able to cut it off before it gets started, so I don't have to be pulling myself out 3 or 4 days later. At this point I'm still blaming my menstrual cycle.