'I had been exhausted for as long as I could remember. Then, I made the decision to see doctor.'

Last winter, I was so unwell for such a long time I convinced myself that something was wrong – seriously wrong.

I had been exhausted for as long as I could remember. I’d recover from one cold, only to be hit by another within days.

For months, I barely got off the couch. I stopped making plans with my friends altogether, because I knew that even if by some fluke I wasn’t bedridden with flu symptoms, I’d probably still be too exhausted to sit up let alone venture out of my apartment.

I was tired all the time; ready-for a-nap-as-soon-as-I-woke-up tired. And I was constantly, constantly sick with a sore throat, runny nose and a cough.

As someone who had always been susceptible to colds, and at first I thought it was just a run of particularly bad luck. Then I thought my shattered immune system might have been the result of prolonged stress.

But by mid-winter, I was at the end of my tether. So I booked a doctor’s appointment - only to be told I just had the flu, and that I should drink orange juice and take vitamin C tablets.

I felt uneasy about the doctor’s diagnosis, to say the least. I am far from a hypochondriac, and I rarely make doctor’s appointments, especially not for a sniffle. But at the same time, I trusted the doctor, and told myself he was probably right, and that I was fine and just unlucky.

Only, I didn’t get better. Not at all. I booked an appointment with a different doctor. I explained that my symptoms were not normal. And I faced my life-long fear of needles, and asked for a blood test.

Within days, I finally had an answer – low vitamin D levels. Looking back now, it’s hard to describe exactly how much of a relief it was to finally know that I hadn’t been imagining all my symptoms, and that the problem could be easily fixed.

At that point, I knew nothing about vitamin D apart from the fact that you got it from the sun.

But my new doctor patiently explained that deficiencies were very common, and that they wreaked havoc with immunity.

I was immediately put on vitamin D tablets with an added dose of calcium (as vitamin D deficiencies can also affect your bones) and slowly, step by step, I started to improve.

I could get through the workday without seriously considering napping under my desk.

I didn’t wake up in the morning feeling like I’d been hit by a truck.

And best of all? I had the energy to actually see all my friends that’d I’d been neglecting the entire winter.

Last week, I had another blood test to see how my vitamin D levels were doing after being on supplements for a few months, and I’m chuffed to report there’s been a huge improvement. I’m still taking my daily dose, and will need to keep getting semi-regular blood tests for the near future – but it’s worth it. It’s so, so worth it.

If you’ve never had your health hijacked by a vitamin D deficiency, it’s probably hard to understand the massive impact it can have on your life. In hindsight, I was a barely-functioning shell. But now? I have energy. I make plans, and have a social life. I just feel healthy – in other words, I’m back to normal.

I want to kick myself for waiting so long to get tested – so if you’re feeling run down, tired and sore, please – just do it.

Disclaimer: Mamamia does not purport to give medical advice. If you have any concerns about your vitamin D levels - or any other health worries - you should make an appointment to see your doctor.

Do you or someone you know struggle with low vitamin D levels?