I'm so tired I can't exercise, how can I up my energy?

Up until 6 months ago I was maintaining my weight, excercising regularly including kick boxing and circuit training and had plenty of energy. However in May Mum was diagnosed with pancreatic cancer and we have been doing 4 x 200 mile return journeys per week to visit all summer (inc a full time job!), and since her discharge have been caring for her at our home. Alongside this, I have started having Zoladex injections (on month 4). My weight is going up, but I realise this is not so much what I am eating, more the fact that I am not having time to eat all day then having a large (unsuitable) meal late at night! I have tried my best to keep up the gym, running the York 10k in 1 hour 13 mins in August (having never run before and only starting training in May). My problem is that now I am SOOOOOO tired, it usually hits me particularly badly about 3/4 pm. I am still pushing myself in the gym but the sheer tiredness makes me feel sick, and now I am struggling to run, in fact last training session I had to call it a day 3 miles in. Do you have any suggestions as to supplements/foods which might help boost my energy levels until I get myself through this difficult period?? I take omega 3, black cohosh and agnus castus (I, forgot to say, the flushes caused by the implant keep me up all night so not sleeping too well either). I have also just started taking 'maca', can too many supplements have an adverse affect?? Any advice gladly received as my body clearly isnt appreciating how hard I am working, and treating me as though I was a couch potato. I have now increased by a full size and dont know what to do! Thanks